The lack of scientific attention devoted to the placebo effect as a phenomenon in its own right probably reflects the paucity of theoretical positions within which to organize the existing data and design new research. This research proposal addresses the clinical significance of behavior-immune system interactions, and will advance the analysis of the placebo effect from a descriptive to an experimental analysis as a reflection of learning processes. Conditioning is an inherent component of most pharmacotherapeutic regimens. The proposed research will capitalize on conditioned immunosuppressive responses to reduce the cumulative amount of cyclosporin medication used in the treatment of psoriasis. Patients would continue to be treated with cyclosporin, but experimental patients would be shifted from their current schedule of continuous reinforcement (active drug whenever medication is taken) to a partial schedule of reinforcement (active drug a percentage of the time and placebo at other times). To equate amounts of medication, other patients would be treated with a reduced dose of cyclosporin in a standard treatment regimen. It is hypothesized that, holding the cumulative dose constant, a partial schedule of reinforcement will enable patients to maintain a lower cumulative amount of cyclosporin than patients treated under a continuous schedule of active drug. Psoriasis is an especially appropriate model to evaluate the therapeutic effect of partial schedules of pharmacologic reinforcement, which could decrease the amount of total drug required and the deleterious "side" effects of long-term cyclosporin treatment. It may be possible to increase the benefit:/risk ratio of drug therapy and reduce the costs of medication. The proposed research is not an attempt to offer a behavioral alternative to drug treatment; it is an attempt to add a behavioral dimension to the design of drug treatment protocols allowing for the reduction in the dosage of immunosuppressive medication. This is the first attempt to adopt conditioning principles and use schedules of reinforcement to design regimens of systemic drug therapy. If proven effective, this new approach to pharmacotherapy and placebo effects is likely to stimulate new interdisciplinary research in neuropharmacology and behavioral pharmacology for the treatment of inflammatory and other chronic disease.